Also known as: EV-DO, EVDO, 1xEV-DO, Evolution-Data Optimized, IS-856
EV-DO (Evolution-Data Optimized, also 1xEV-DO or IS-856) is the high-speed data member of the CDMA2000 family. It dedicates an entire 1.25 MHz CDMA carrier to packet data and, rather than sharing the downlink by code alone, time-multiplexes it: the base station transmits at full power to one best-placed user at a time, choosing the data rate from that user’s reported channel quality.1
Overview
CDMA2000 1xRTT carried voice and data together, which capped data performance. EV-DO (“DO” for data-optimized) splits data onto its own carrier and optimises purely for throughput. The downlink is time-division multiplexed in 1.67 ms slots; each terminal continuously reports the best rate its channel can sustain (a data rate control signal), and a proportional-fair scheduler picks who to serve. Adaptive modulation from QPSK up to 16-QAM and hybrid ARQ push peak rates well above 1xRTT. This is conceptually parallel to HSPA on the W-CDMA side.
Technical characteristics
| Property | Value |
|---|---|
| Generation | 3G data |
| Family | CDMA2000 (IS-856) |
| Carrier spacing | 1.25 MHz (dedicated to data) |
| Downlink | Time-multiplexed, full-power to one user per slot |
| Slot length | 1.67 ms |
| Modulation | QPSK, 8PSK, 16-QAM (adaptive) |
| Peak (Rev. A) | ≈3.1 Mbit/s down, ≈1.8 Mbit/s up |
| Rate control | Per-user DRC feedback, proportional-fair scheduling |
Giving the whole carrier to one user at a time, at full power, is what lets EV-DO reach high peak rates despite the narrow 1.25 MHz channel.
History
EV-DO was standardised by 3GPP2 as IS-856 and reached networks from about 2002 (Release 0), with Revisions A and B raising uplink rates and adding multi-carrier bonding. It gave CDMA2000 operators a mobile-broadband answer to UMTS HSPA during the 3G era.
Deployment
EV-DO powered mobile broadband for CDMA carriers in the US, South Korea, and elsewhere, delivered through phones and USB modems. As those operators moved to LTE for 4G, EV-DO and the rest of CDMA2000 were phased out and their carriers refarmed.
Decoding it with GopherTrunk
GopherTrunk scans trunked land-mobile and utility signals; cellular data such as EV-DO is out of scope and is not decoded. It carries private, authenticated, ciphered subscriber traffic on licensed CDMA2000 spectrum. EV-DO is documented here only for reference within the 3G family.